A couple things to keep in mind.
Some people like to preserve the delicate bones in the nasal passage, if you like them be very careful not to break them when cleaning that area. If you don't care, they can be broken away from the skull to leave a simple hole there.
Beetles are the best if you have access to them, very fast, does a good job and YOU don't have to much of the work. To speed up the process you can take out the eyes, tounge and cheek muscules.
If you choose to boil, take it slow. Just simmer the meat. The teeth may fall out, so don't just chuck the water out the door without looking first (does that sound like the voice of experience?). Use an old screw driver or something similar to loosen up the brains and help them out the hole. A stiff brush can be useful. Also, you can let the skull dry and some missed areas might show up, you can use a little sand paper.
Many here mentioned various ways to whiten the bone. Some people also like the "natural" coloration, take a good look at the skull before whitening to be sure you would not rather leave it as is.
One way NOT to clean a skull is to soak it in a bucket of water for 2 days, and then scrape it clean be hand. Some guy told me to do this, I was gulable enough to listen. It turns a somewhat dirty job into a disgusting job.
Juniper Bow